The present invention relates to a display control system, which connects a display controller having an image memory for storing image information, and a plurality of display devices, and controls the plurality of display devices to display an image on the basis of the image information, and its control method.
The present invention also relates to a switching device and connection device, which connect a plurality of peripheral devices to a single host equipment, and a peripheral device system using these devices. More specifically, the present invention relates to a switching device which connects a plurality of printers to a host computer having one printer interface, and a peripheral device system. Furthermore, the present invention relates to a branch device suitable for building a display system that connects a plurality of display devices to a single host equipment to display, a peripheral device system using that device, and their control method.
As a display device for a computer equipment or the like, a CRT display device is generally known. However, since the CRT display device requires a considerable depth in the thickness direction of its display screen, it has a large volume as a whole, and the entire system can hardly be made compact. Display control of such CRT display device must use a CRTC (CRT controller) or the like to refresh display data, and is complex.
As a display device that can compensate for the shortcomings of such conventional CRT display device, a liquid crystal display device, which can realize a size reduction, especially, a low-profile structure, of the display device, is known. Of such liquid crystal device, a display device (to be referred to as an FLCD: FLC display hereinafter) using a ferroelectric liquid crystal (to be abbreviated as FLC hereinafter) is known. As one of the features of the FLCD, its liquid crystal cells retain their display states upon application of an electric field. That is, the FLCD has very low-profile liquid crystal cells, in each of which an elongated FLC element orients itself in a first or second stable state according to the applied direction of the electric field, and maintains its orientation state after the electric field is removed. With the bistability of the FLC elements, the FLCD using such feature has memory characteristics of the display state. Such FLC and FLCD are described in detail in, e.g., U.S. Pat. No. 4,964,699.
A display controller for such FLCD need not refresh the screen all the time unlike a CRT display controller. By preferentially updating the display contents of a display area corresponding to a portion where the contents of a display memory have been updated, data can be displayed even on a large screen without dropping the refresh rate.
As an application of such display device, in events such as exhibitions, demonstrations, and the like held in broad sites, a plurality of display devices are set, and identical image information is displayed on these display devices, thus providing identical image information to many people.
On the other hand, as a display control system that displays different contents of image information on a plurality of display devices, the following three systems are known.
(1) LAN-connected System
A plurality of host computers are connected via a LAN, and display devices are connected to these host computers via display controllers.
(2) System Using a Plurality of Graphic Sub-systems
A plurality of display controllers are connected to a single host computer. Display devices are connected to these display controllers.
(3) Display Memory Dividing System
A display memory on a single host computer and single display controller is logically divided into a plurality of memory areas, which are assigned to a plurality of display devices connected.
However, in order to output identical or different image information contents to a plurality of conventional display devices, display controllers for controlling the display devices are required in correspondence with the number of display devices.
Especially, in order to display different image information contents to a plurality of display devices, the above-mentioned systems respectively have the following shortcomings.
(1) LAN-connected System
This system requires high cost since one display device requires one each host computer and display controller. Since a plurality of host computers must be controlled, a large-scale, complex control program is required.
(2) System Using a Plurality of Graphic Sub-systems
This system requires high cost since one display device requires a single display controller. Also, since the number of display controllers that can be connected to a single host computer is limited, the number of display devices that can be connected is inevitably limited.
(3) Display Memory Dividing System
Data must be sequentially read out from a plurality of divided memory areas. For this reason, the number of display devices that can be connected is limited by the read speed from the display memory.
On the other hand, a switching device shown in FIG. 19 is generally known. By switching a switch 3 provided to a switching device 332, one of two printers 334a and 334b is selected to print. When such switching devices are connected in series with each other, as shown in FIG. 20, one of a plurality of printers 334a to 334c can be selected. FIG. 21 shows an arrangement for selecting one of printers 334a to 334e using more switching devices 332a to 332d. 
When the number of printers connected increases, and the number of switching devices increases, the total length of connection cables between adjacent switching devices becomes large, and the load viewed from a host computer 331 increases. For this reason, each switching device requires a circuit for shaping the signal waveform, and the like. Operating such waveshaping circuit and the like requires electric power. Hence, the individual switching devices have power supplies and power switches 335a to 335d for turning on/off these power supplies (FIG. 21).
In a display system that connects a plurality of displays to a single host equipment, as shown in FIG. 27, displays 4100, 4120, and 4130 are connected via branch switches 4202, 4203, and 4204.
However, in the arrangement shown in FIG. 21, in order to print using the printer 334d, all the power switches 335a to 335d of the switching devices 332a to 332d must be manually turned on by the user.
When the printers 334a and 334b are used but the printers 334c to 334e are not used, the power switches 335a and 335b of the switching devices 332a and 332b must be turned on, but the power switches 335c and 335d of the switching devices 332c and 332d need not be turned on. In terms of power savings, these switching devices 332c and 332d are preferably kept OFF. Such combination of the ON states of the power switches 335a to 335d must also be determined by the user.
Furthermore, since some switching devices have ON power switches and some other have OFF power switches, the user sometimes forgets to turn off such power switches.
In the above-mentioned display system which includes the branch connectors which distribute and supply image data from the host equipment to a plurality of displays, as the numbers of displays and branch connectors become larger, the user must turn on/off a larger number of switches every time the system is activated/deactivated, resulting in a heavy load on the user.
The present invention has been made in consideration of the above-mentioned problems, and has as its object to provide a flexible display control system, which can control a plurality of display devices by a single display controller and is not restrained by the number of display devices connected, its control method, and a computer readable memory.
It is another object of the present invention to provide a switching device which automatically turns on/off required power supplies on the basis of the ON/OFF states of the power supplies in peripheral devices connected, a peripheral device system using the switching device, and a computer readable memory.
It is still another object of the present invention to provide a connection device which can control to automatically supply electric power to a peripheral device to be driven in response to an instruction from a host equipment, a peripheral device system using the connection device, and a computer readable memory.
It is still another object of the present invention to provide a peripheral device system which connects a plurality of peripheral devices by branching them from a single communication bus, and which can attain communications associated with control information other than the data to be processed by the respective peripheral devices by a lower-cost arrangement, a connection device and peripheral device used in the system, their control method, and a computer readable memory.
It is still another object of the present invention to provide a peripheral device system which connects a plurality of peripheral devices by branching them from a single communication bus, and which permits one of a plurality of peripheral devices to communicate the control information and automatically denies other peripheral devices from communicating the control information, a connection device and peripheral device used in the system, their control method, and a computer readable memory.
It is still another object of the present invention to provide a connection device which automatically determines the peripheral device that communicates the control information, and other peripheral devices in a peripheral device system which connects a plurality of peripheral devices by branching them from a single communication bus and controls the peripheral devices to display identical image data, its control method, and a computer readable memory.
It is still another object of the present invention to provide a peripheral device which automatically determines the peripheral device that communicates the control information, and other peripheral devices in a peripheral device system which connects a plurality of peripheral devices by branching them from a single communication bus and controls the peripheral devices to display different image data, its control method, and a computer readable memory.
In order to achieve the above objects, a display control system according to the present invention comprises the following arrangement.
That is, a display control system which connects a display controller having an image memory for storing image information to a plurality of display devices, and controls the plurality of display devices to display an image on the basis of the image information, comprises:
monitoring means for monitoring a presence/absence of an image information request signal output from each of the plurality of display devices; and
distribution means for distributing the image information stored in the image memory of the display controller to each of the plurality of display devices on the basis of a monitoring result of the monitoring means.
In order to achieve the above objects, a method of controlling a display control system according to the present invention comprises the following arrangement.
That is, a method of controlling a display control system which connects a display controller having an image memory for storing image information to a plurality of display devices, and controls the plurality of display devices to display an image on the basis of the image information, comprises:
the monitoring step of monitoring a presence/absence of an image information request signal output from each of the plurality of display devices; and
the distribution step of distributing the image information stored in the image memory of the display controller to each of the plurality of display devices on the basis of a monitoring result in the monitoring step.
In order to achieve the above objects, a display control system according to the present invention comprises the following arrangement.
That is, a display control system which connects a display controller having an image memory for storing image information to a plurality of display devices, and controls the plurality of display devices to display an image on the basis of the image information, comprises:
designation means for designating a destination display device of the image information; and
control means for controlling the display device designated by the designation means to display the image based on the image information.
In order to achieve the above objects, a method of controlling a display control system according to the present invention comprises the following arrangement.
That is, a method of controlling a display control system which connects a display controller having an image memory for storing image information to a plurality of display devices, and controls the plurality of display devices to display an image on the basis of the image information, comprises:
the designation step of designating a destination display device of the image information; and
the control step of controlling the display device designated in the designation step to display the image based on the image information.
In order to achieve the above objects, a computer readable memory according to the present invention comprises the following arrangement.
That is, a computer readable memory which stores a program code for controlling a display control system which connects a display controller having an image memory for storing image information to a plurality of display devices, and controls the plurality of display devices to display an image on the basis of the image information, comprises:
a program code of the monitoring step of monitoring a presence/absence of an image information request signal output from each of the plurality of display devices; and
a program code of the distribution step of distributing the image information stored in the image memory of the display controller to each of the plurality of display devices on the basis of a monitoring result in the monitoring step.
In order to achieve the above objects, a computer readable memory according to the present invention comprises the following arrangement.
That is, a computer readable memory which stores a program code for controlling a display control system which connects a display controller having an image memory for storing image information to a plurality of display devices, and controls the plurality of display devices to display an image on the basis of the image information, comprises:
a program code of the designation step of designating a destination display device of the image information; and
a program code of the control step of controlling the display device designated in the designation step to display the image based on the image information.
In order to achieve the above objects, a switching device according to the present invention comprises the following arrangement.
That is, a switching device for forming a communication path between a host equipment and a plurality of peripheral devices, comprises:
input means for receiving a signal representing a power supply state which indicates if a power supply of a peripheral device connected to a line on the peripheral device side is ON or OFF;
supply means for supplying electric power to the peripheral device when the signal indicates the ON power supply state; and
output means for outputting the supply state of electric power by the supply means onto a line on the host equipment side as the power supply state of the peripheral device.
In order to achieve the above objects, a method of controlling a switching device according to the present invention comprises the following arrangement.
That is, a method of controlling a switching device for forming a communication path between a host equipment and a plurality of peripheral devices, comprises:
the input step of receiving a signal representing a power supply state which indicates if a power supply of a peripheral device connected to a line on the peripheral device side is ON or OFF;
the supply step of supplying electric power to the peripheral device when the signal indicates the ON power supply state; and
the output step of outputting the supply state of electric power in the supply step onto a line on the host equipment side as the power supply state of the peripheral device.
In order to achieve the above objects, a computer readable memory according to the present invention comprises the following arrangement.
That is, a computer readable memory which stores a program code for controlling a switching device for forming a communication path between a host equipment and a plurality of peripheral devices, comprises:
a program code of the input step of receiving a signal representing a power supply state which indicates if a power supply of a peripheral device connected to a line on the peripheral device side is ON or OFF;
a program code of the supply step of supplying electric power to the peripheral device when the signal indicates the ON power supply state; and
a program code of the output step of outputting the supply state of electric power in the supply step onto a line on the host equipment side as the power supply state of the peripheral device.
In order to achieve the above objects, a peripheral device system according to the present invention comprises the following arrangement.
That is, a peripheral device system which has a host equipment, a plurality of peripheral devices, and a plurality of switching devices for forming a communication path therebetween, comprises:
first output means for outputting a signal representing a power supply state which indicates if its own power supply is ON or OFF from each of the plurality of peripheral devices;
input means for receiving a signal representing a power supply state which indicates if a power supply of a peripheral device connected to a line on the peripheral device side is ON or OFF, in each of the plurality of switching devices;
supply means for supplying electric power to the switching device when the signal indicates the ON power supply state; and
second output means for outputting the supply state of electric power by the supply means onto a line on the host equipment side as the power supply state of the switching device.
In order to achieve the above objects, a method of controlling a peripheral device system according to the present invention comprises the following arrangement.
That is, a method of controlling a peripheral device system which has a host equipment, a plurality of peripheral devices, and a plurality of switching devices for forming a communication path therebetween, comprises:
the first output step of outputting a signal representing a power supply state which indicates if its own power supply is ON or OFF from each of the plurality of peripheral devices;
the input step of receiving a signal representing a power supply state which indicates if a power supply of a peripheral device connected to a line on the peripheral device side is ON or OFF, in each of the plurality of switching devices;
the supply step of supplying electric power to the switching device when the signal indicates the ON power supply state; and
the second output step of outputting the supply state of electric power by the supply means onto a line on the host equipment side as the power supply state of the switching device.
In order to achieve the above objects, a computer readable memory according to the present invention comprises the following arrangement.
That is, a computer readable memory which stores a program code for controlling a peripheral device system which has a host equipment, a plurality of peripheral devices, and a plurality of switching devices for forming a communication path therebetween, comprises:
a program code of the first output step of outputting a signal representing a power supply state which indicates if its own power supply is ON or OFF from each of the plurality of peripheral devices;
a program code of the input step of receiving a signal representing a power supply state which indicates if a power supply of a peripheral device connected to a line on the peripheral device side is ON or OFF, in each of the plurality of switching devices;
a program code of the supply step of supplying electric power to the switching device when the signal indicates the ON power supply state; and
a program code of the second output step of outputting the supply state of electric power by the supply means onto a line on the host equipment side as the power supply state of the switching device.
In order to achieve the above objects, a connection device according to the present invention comprises the following arrangement.
That is, a connection device for forming a communication path between a host equipment and a plurality of peripheral devices, comprises:
holding means for holding a set identification number;
detection means for detecting identification information output from the host equipment;
determination means for determining based on the identification information detected by the detection means and the identification number held in the holding means if electric power is to be supplied; and
control means for controlling power supply to the peripheral device connected to the connection device on the basis of a determination result of the determination means.
In order to achieve the above objects, a method of controlling a connection device according to the present invention comprises the following arrangement.
That is, a method of controlling a connection device for forming a communication path between a host equipment and a plurality of peripheral devices, comprises:
the holding step of holding a set identification number in a storage medium;
the detection step of detecting identification information output from the host equipment;
the determination step of determining based on the identification information detected in the detection step and the identification number held in the storage medium in the holding step if electric power is to be supplied; and
the control step of controlling power supply to the peripheral device connected to the connection device on the basis of a determination result in the determination step.
In order to achieve the above objects, a computer readable memory according to the present invention comprises the following arrangement.
That is, a computer readable memory which stores a program code for controlling a connection device for forming a communication path between a host equipment and a plurality of peripheral devices, comprises:
a program code of the holding step of holding a set identification number in a storage medium;
a program code of the detection step of detecting identification information output from the host equipment;
a program code of the determination step of determining based on the identification information detected in the detection step and the identification number held in the storage medium in the holding step if electric power is to be supplied; and
a program code of the control step of controlling power supply to the peripheral device connected to the connection device on the basis of a determination result in the determination step.
In order to achieve the above objects, a peripheral device system according to the present invention comprises the following arrangement.
That is, a peripheral device system which has a host equipment, a plurality of peripheral devices, and a plurality of switching devices for forming a communication path therebetween, comprises:
holding means for holding an identification number set in the connected peripheral device in each of the plurality of switching devices;
detection means for detecting identification information output from the host equipment;
determination means for determining based on the identification information detected by the detection means and the identification number held in the holding means if electric power is to be supplied; and
control means for controlling power supply to the peripheral device connected to the connection device on the basis of a determination result of the determination means.
In order to achieve the above objects, a method of controlling a peripheral device system according to the present invention comprises the following arrangement.
That is, a method of controlling a peripheral device system which has a host equipment, a plurality of peripheral devices, and a plurality of switching devices for forming a communication path therebetween, comprises:
the holding step of holding, in a storage medium, an identification number equal to an identification number set in the connected peripheral device in each of the plurality of switching devices;
the detection step of detecting identification information output from the host equipment;
the determination step of determining based on the identification information detected in the detection step and the identification number held in the storage medium in the holding step if electric power is to be supplied; and
the control step of controlling power supply to the peripheral device connected to the connection device on the basis of a determination result in the determination step.
In order to achieve the above objects, a computer readable memory according to the present invention comprises the following arrangement.
That is, a computer readable memory which stores a program code for controlling a peripheral device system which has a host equipment, a plurality of peripheral devices, and a plurality of switching devices for forming a communication path therebetween, comprises:
a program code of the holding step of holding, in a storage medium, an identification number equal to an identification number set in the connected peripheral device in each of the plurality of switching devices;
a program code of the detection step of detecting identification information output from the host equipment;
a program code of the determination step of determining based on the identification information detected in the detection step and the identification number held in the storage medium in the holding step if electric power is to be supplied; and
a program code of the control step of controlling power supply to the peripheral device connected to the connection device on the basis of a determination result in the determination step.
In order to achieve the above objects, a connection device according to the present invention comprises the following arrangement.
That is, a connection device for connecting a plurality of peripheral devices to a single information output device, comprises:
a first communication path which is connected to an input-side device, output-side device, and a peripheral device, receives information to be processed by the peripheral device from the input-side device, and outputs the information to be processed to the peripheral device and the output-side device;
a second communication path used for making a communication of control information between the input-side device and the peripheral device;
determination means for trying a communication with the input-side device using the second communication path, and determining based on the trial result if the communication of the control information is to be made; and
path control means for forming the second communication path between the input-side device and the peripheral device when the determination means determines that the communication of the control information is to be made.
In order to achieve the above objects, a peripheral device according to the present invention comprises the following arrangement.
That is, a peripheral device for processing data to be processed output from an information processing apparatus, comprises:
first communication means for receiving the data to be processed;
second communication means for making a communication of control information with the information processing apparatus;
determination means for observing a communication state of the second communication means, and determining based on the communication state if the communication of the control information is to be executed; and
control means for making the communication of the control information with the information processing apparatus via the second communication means when the determination means determines that the communication of the control information is to be executed.
In order to achieve the above objects, a method of controlling a connection device according to the present invention comprises the following arrangement.
That is, a method of controlling a connection device which comprises a first communication path which is connected to an input-side device, output-side device, and a peripheral device, receives information to be processed by the peripheral device from the input-side device, and outputs the information to be processed to the peripheral device and the output-side device, and a second communication path used for making a communication of control information between the input-side device and the peripheral device, comprises:
the determination step of trying a communication with the input-side device using the second communication path, and determining based on the trial result if the communication of the control information is to be made; and
the path control step of forming the second communication path between the input-side device and the peripheral device when it is determined in the determination step that the communication of the control information is to be made.
In order to achieve the above objects, a computer readable memory according to the present invention comprises the following arrangement.
That is, a computer readable memory which stores a program code for controlling a connection device which comprises a first communication path which is connected to an input-side device, output-side device, and a peripheral device, receives information to be processed by the peripheral device from the input-side device, and outputs the information to be processed to the peripheral device and the output-side device, and a second communication path used for making a communication of control information between the input-side device and the peripheral device, comprises:
a program code of the determination step of trying a communication with the input-side device using the second communication path, and determining based on the trial result if the communication of the control information is to be made; and
a program code of the path control step of forming the second communication path between the input-side device and the peripheral device when it is determined in the determination step that the communication of the control information is to be made.
In order to achieve the above objects, a method of controlling a peripheral device according to the present invention comprises the following arrangement.
That is, a method of controlling a peripheral device which comprises first communication means for receiving data to be processed, and second communication means for making a communication of control information with an information processing apparatus, and processes the data to be processed output from the information processing apparatus, comprises:
the determination step of observing a communication state of the second communication means, and determining based on the communication state if the communication of the control information is to be executed; and
the control step of making the communication of the control information with the information processing apparatus via the second communication means when it is determined in the determination step that the communication of the control information is to be executed.
In order to achieve the above objects, a computer readable memory according to the present invention comprises the following arrangement.
That is, a computer readable memory which stores a program code for controlling a peripheral device which comprises first communication means for receiving data to be processed, and second communication means for making a communication of control information with an information processing apparatus, and processes the data to be processed output from the information processing apparatus, comprises:
a program code of the determination step of observing a communication state of the second communication means, and determining based on the communication state if the communication of the control information is to be executed; and
a program code of the control step of making the communication of the control information with the information processing apparatus via the second communication means when it is determined in the determination step that the communication of the control information is to be executed.
In order to achieve the above objects, a peripheral device system according to the present invention comprises the following arrangement.
That is, a peripheral device system for connecting a single information processing apparatus and a plurality of peripheral devices via a plurality of connection devices, comprises:
communication control means for transmitting data to be processed by the peripheral device from the information processing apparatus to each of the plurality of peripheral devices;
selection means for selecting one peripheral device which executes a communication of control information between the information processing apparatus and the peripheral device from the plurality of peripheral devices; and
communication control means for permitting the peripheral device selected by the selection means to execute the communication of the control information with the information processing apparatus, and inhibiting other peripheral devices from executing communication of the control information.
In order to achieve the above objects, a method of controlling a peripheral device system according to the present invention comprises the following arrangement.
That is, a method of controlling a peripheral device system for connecting a single information processing apparatus and a plurality of peripheral devices via a plurality of connection devices, comprises:
the communication control step of transmitting data to be processed by the peripheral device from the information processing apparatus to each of the plurality of peripheral devices;
the selection step of selecting one peripheral device which executes a communication of control information between the information processing apparatus and the peripheral device from the plurality of peripheral devices; and
the communication control step of permitting the peripheral device selected in the selection step to execute the communication of the control information with the information processing apparatus, and inhibiting other peripheral devices from executing communication of the control information.
In order to achieve the above objects, a computer readable memory according to the present invention comprises the following arrangement.
That is, a computer readable memory which stores a program code for controlling a peripheral device system for connecting a single information processing apparatus and a plurality of peripheral devices via a plurality of connection devices, comprises:
a program code of the communication control step of transmitting data to be processed by the peripheral device from the information processing apparatus to each of the plurality of peripheral devices;
a program code of the selection step of selecting one peripheral device which executes a communication of control information between the information processing apparatus and the peripheral device from the plurality of peripheral devices; and
a program code of the communication control step of permitting the peripheral device selected in the selection step to execute the communication of the control information with the information processing apparatus, and inhibiting other peripheral devices from executing communication of the control information.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.